In a conventional semiconductor device, if the semiconductor element (e.g. a MOFSET (a metal-oxide-semiconductor field-effect transistor)) that is being used as a semiconductor relay shorts out, the semiconductor element itself is prevented from burning and an electrical line and a load on the downstream side are protected by cutting off the electric current with a fuse mechanism provided within the semiconductor element package.
There are many cases in which a plurality of semiconductor elements (semiconductor relays) connected in parallel are used to increase the current capacity. There are also many cases in which a pair of semiconductor elements connected in anti-series are used such that a counter-current does not pass through via a body diode (a parasitic diode).
Patent Document 1 discloses a semiconductor device with an incorporated fuse including a conductor pattern, a fuse mechanism and a wire. The conductor pattern is formed adjacent to the semiconductor device on a circuit board and includes a groove formed in its upper surface. The fuse mechanism includes an electrode formed with a metal material with a low melting point in an area that includes an upper surface of the pattern and the edge at one end of the groove. One end of the wire is connected to an electrode of the semiconductor device and the other end is connected to the electrode of the fuse mechanism. When an overcurrent flows through the pattern, the electrode of the fuse mechanism melts and flows into the groove, the other end of the wire is disconnected from the electrode, and the semiconductor device and the pattern are cut off from each other.